Synthetic chromanol derivatives and their interaction with complex III in mitochondria from bovine, yeast, and Leishmania.

Synthetic chromanol derivatives (TMC4O, 6-hydroxy-2,2,7,8-tetramethyl-chroman-4-one; TMC2O, 6-hydroxy-4,4,7,8-tetramethyl-chroman-2-one; and Twin, 1,3,4,8,9,11-hexamethyl-6,12-methano-12H-dibenzo[d,g][1,3]dioxocin-2,10-diol) share structural elements with the potent inhibitor of the mitochondrial cytochrome (cyt) bc(1) complex stigmatellin. Studies with isolated bovine cyt bc(1) complex demonstrated that these compounds partially inhibit the mammalian enzyme. The aim of this work was to comparatively investigate these toxicological aspects of synthetic vitamin E derivatives in mitochondria of different species. The chromanols and atovaquone as reference compound were evaluated for their inhibition of the cyt bc(1) activity in mitochondrial fractions from bovine hearts, yeast, and Leishmania. In addition, compounds were evaluated in vitro for their inhibitory activity against whole-cell Leishmania and mouse peritoneal macrophages. In these organisms, the chromanols showed a species-selective inhibition of the cyt bc(1) activity different from that of atovaquone. While in atovaquone the side chain mediates species-selectivity, the marked differences for TMC2O and TMC4O in cyt bc(1) inhibition suggests that direct substitution of the chromanol headgroup will control selectivity in these compounds. Low micromolar concentrations of TMC2O (IC(50) = 9.5 ± 0.5 µM) inhibited the growth of Leishmania, and an esterified TMC2CO derivative inhibited the cyt bc(1) activity with an IC(50) of 4.9 ± 0.9 µM. These findings suggest that certain chromanols also exhibit beyond their antioxidative properties antileishmanial activities and that TMC2O derivatives could be useful toward the development of highly active antiprotozoal compounds.

Antimicrobial evaluation of the polyisoprenylated benzophenones nemorosone and guttiferone A.

Polyisoprenylated benzophenones have been isolated from plants, particularly in the Clusiaceae family, and their biological properties recently have received considerable attention from a pharmacological point of view. The aim of the study was to investigate the polyisoprenylated benzophenones, nemorosone and guttiferone A, for their antimicrobial effect against a panel of bacteria, fungi and protozoan parasites. They showed a moderate activity against the Gram-positive bacterium Staphylococcus aureus, while no activity was demonstrated against Escherichia coli and the fungi Trichophyton rubrum and Candida albicans. An interesting activity was found for Plasmodium falciparum with IC50 values lower than 1 µm, while cytotoxicity on MRC-5 cells revealed CC50 values of 15.5 and 12.0 µm, respectively, for nemorosone and guttiferone A.

Heat-shock protein 70 PCR-RFLP: a universal simple tool for Leishmania species discrimination in the New and Old World.

INTRODUCTION: Species typing in leishmaniasis gains importance in diagnostics, epidemiology, and clinical studies. A restriction fragment length polymorphism (RFLP) assay of PCR amplicons from a partial heat-shock protein 70 gene (hsp70) had been described for the New World, allowing identification of some species. METHODS: Based on an initial in silico analysis of 51 hsp70 sequences, most of which we recently determined in the frame of a phylogenetic study, species-specific restriction sites were identified. These were tested by PCR-RFLP on 139 strains from 14 species, thereby documenting both inter- and intra-species variability. RESULTS: Our assay could identify Leishmania infantum, L. donovani, L. tropica, L. aethiopica, L. major, L. lainsoni, L. naiffi, L. braziliensis, L. peruviana, L. guyanensis, and L. panamensis by applying 2 subsequent digests. L. mexicana, L. amazonensis, and L. garnhami did not generate species-specific restriction fragment patterns. CONCLUSION: Currently no assay is available for global Leishmania species discrimination. We present a universal PCR-RFLP method allowing identification of most medically relevant Old and New World Leishmania species on the basis of a single PCR, obviating the need to perform separate PCRs. The technique is simple to perform and can be implemented in all settings where PCR is available.

Antileishmanial activity of essential oil from Chenopodium ambrosioides and its main components against experimental cutaneous leishmaniasis in BALB/c mice.

UNLABELLED: Chenopodium ambrosioides have been used during centuries by native people to treat parasitic diseases. AIMS OF THE STUDY: To compare the in vivo anti-leishmanial activity of the essential oil (EO) from C. ambrosioides and its major components (ascaridole, carvacrol and caryophyllene oxide). MATERIALS AND METHODS: Anti-leishmanial effect was evaluated in BALB/c mice infected with Leishmania amazonensis and treated with the EO, main compounds and artificial mix of pure components by intralesional route at 30 mg/kg every 4 days during 14 days. Diseases progression and parasite burden in infected tissues were determined. RESULTS: EO prevented lesion development compared (p<0.05) with untreated animals and treated with vehicle. In addition, the efficacy of EO was also statistically superior (p<0.05) compared with the glucantime-treated animals. No potential effects were observed with pure components treatment. Mix of pure compounds cause death of animals after 3 days of treatment. CONCLUSIONS: Our results demonstrate the superiority of EO against experimental cutaneous leishmaniasis caused by L. amazonensis.

In vitro activity of an essential oil against Leishmania donovani.

The in vitro antileishmanial effect of the essential oil from Chenopodium ambrosioides against Leishmania donovani was investigated. The product showed significant activity against promastigotes and amastigotes, with a 50% effective concentration of 4.45 and 5.1 microg/mL, respectively. The essential oil caused an irreversible inhibition of the growth of promastigotes after a treatment with 100 or 10 microg/mL for 1 or 24 h, respectively. The phagocytic activity of the macrophages was preserved at a concentration toxic to the parasite. The essential oil from C. ambrosioides may be a potential candidate drug to development a new agent to combat this parasitic disease.